Most books on complexity theory promise to lead the epistemological thrill-seeker far out on the limb of theory. Not so Casti ( Searching for Certainty ). He admits early on to a major ``surprise'' about chaos and other formal systems: that even with artificial intelligence as a new tool, theory cannot capture nature. After an almost old-fashioned undergraduate review of basic concepts of dynamical systems, Casti shows how formal complexity models proceed from the basic ``surprises.'' Always more interested in instructing than in dazzling with sensational and obtuse ideas, Casti steers the reader toward an understanding of the field. He's a good teacher and this is the kind of grounding lay readers should have before they step farther out on a new paradigm. (Apr.)